German and Cypriot researchers investigate the impact of the monsoon on air quality and climate change

Since July scientists from the Max Planck Institute for Chemistry and The Cyprus Institute, in a team of 65 international colleagues, are carrying out a research mission to investigate the Earth’s atmosphere with the new German High-altitude Long-range HALO aircraft.

They will study how the self-cleaning capacity of the atmosphere is affected by the Asian monsoon. This self-cleaning property is central in cleaning the air from many pollutants. Short-lived, highly reactive oxidants chemically convert hydrocarbons, such as the greenhouse gas methane and emissions from industry and road traffic, making them more water-soluble and thus allowing them to be removed by rain. Since air pollution in Asia is increasing drastically on a large scale, scientists suspect that this has a global impact on the atmospheric self-cleaning capacity and consequently on air quality and climate change.

“The monsoon rainfalls can wash out many soluble gases and aerosol particles from the atmosphere, however, we do not know how efficient these processes are,” says Jos Lelieveld, Director at the Max Planck Institute for Chemistry and Professor at The Cyprus Institute, who is the principal investigator of the research mission. “Once we understand the chemical and transport processes of the polluted air masses in the Asian monsoon, we can improve predictions of air quality and climate change,” he adds.

Following the name of a detergent, the researchers called their project “OMO”; in science, however, this is an abbreviation of “Oxidation Mechanism Observations”. In more than 120 flight hours with the HALO aircraft, flown from July to the end of August, they cover about 100,000 kilometers in the atmosphere and examine the air downwind of the monsoon above Asia and the Middle East. HALO is a high-flying jet that was specially adjusted for atmospheric research, and is operated by the DLR.

On July 21, 2015, the mission started in Paphos, Cyprus, from where HALO flies towards the Arabian Peninsula and the Arabian Sea. In-between, the aircraft, crew and team changed course to the Maldives to analyze the atmosphere over the Indian Ocean and the Bay of Bengal. Then they came back to Cyprus to track the monsoon outflow for two weeks before the aircraft returns to Germany by the end of August. The research is a collaboration between the German institutes involved in HALO, The Cyprus Institute, the Cyprus Department of Meteorology and builds upon a ground-based measurement campaign with the Air Quality Group of the Department of Labor Inspection that took place in 2014. In Paphos the HALO aircraft is facilitated and supported by EDT Offshore (Limassol).

HALO has a range of about 8,000 kilometers and can fly at an altitude of more than 15 kilometers, hence the researchers can cover flight tracks up to ten hours and also perform vertical profiles to characterize the air masses. In addition to ozone, nitrogen oxides, sulfur dioxides, aerosol particles and volatile organic components, the researchers’ instruments also detect short-lived compounds such as hydroxyl radicals, which are important for the oxidation mechanism of the atmosphere. The hydroxyl radicals are also called the “detergent” of the atmosphere. Satellite data and model calculations will complement the aircraft measurements in the analyses after the flights.